The conversion of the kinetic energy of moving air, the atmospheric wind, to other forms of energy is well known. Windmills have long been used for the pumping of water and in recent years have been used for driving generators for the generation of electricity. The ordinary windmill, where the blade extends radially outward from the axis of rotation, suffers from the problem that the velocity of the blade increases with increasing radius and the angle of attack changes unless the blade is skewed or twisted. The twisted blades have different effects at different rotational speeds. In extracting kinetic energy from the wind, the wind velocity is not known. Consequently, the blade is properly skewed for only one condition. It is desirable to avoid skewed blades.
Seki U.S. Pat. No. 4,247,253 defines a structure wherein the blades are parallel to the axis of revolution. Amick U.S. Pat. No. 4,162,410 defines another structure with axially positioned blades. The Amick structure is also enhanced by the utilization of fixed stator blades to control the direction of wind flow onto the rotating blades. There is no adjustment in the structure for accommodation of different wind velocities. Furthermore, the stator blades present a large wind resistance which requires a strong overall structure.
Accordingly, there is a need for an electricity generating wind turbine which accomplishes the advantages of axially positioned blades and which employs cooperating structure for enhancing the performance of the axial blades, all without presenting excessive structures subject to wind pressure.